Hometriangle calculator
Triangle Calculator
Calculate triangle area, perimeter, and solve the Pythagorean theorem.
Area from base & height
Area = (base \u00d7 height) / 2
12
Heron's formula (all three sides)
Area (Heron's)
6
Perimeter (a+b+c)
12
How to use
- 1Choose 'Area & Perimeter' to calculate area using base & height or Heron's formula with all three sides.
- 2Choose 'Pythagorean Theorem' to find a missing side in a right triangle — select which side to solve for.
- 3Enter the known values and read results instantly.
Triangle Formulas
Area (base & height): A = (b × h) / 2 — multiply the base by the perpendicular height and divide by 2. Works for any triangle type.
Area (Heron's formula): When you know all three sides (a, b, c), calculate the semi-perimeter s = (a+b+c)/2, then A = √(s(s−a)(s−b)(s−c)).
Pythagorean theorem: a² + b² = c² — applies only to right triangles, where c is the hypotenuse (the side opposite the 90° angle). Use it to find any missing side when you know the other two.